There is a long and well-known history to the art of storing the cold of winter so that it can be used for purposes of cooling in summer, starting perhaps with the nineteenth century practice of storing blocks of natural winter ice in sawdust and distributing them in the summer for cold storage of food. The same concept was then applied at least experimentally to the use of natural ice blocks for cooling and dehumidifying ambient air in buildings. More recently it has been proposed to form what are known as "ice ponds" by filling excavated pits with artificial snow in the wintertime, using snow-making equipment familiar to the ski industry, and thermally insulating the deposits of snow. In the summer the melt water from the snow deposits is pumped to the chilled water system of a nearby building when air conditioning is needed and the return water is sprayed back over the snow for recooling. Known variations of this concept include the use of artifically manufactured ice which is shucked into bins or frozen in tanks in place of man-made snow in pits.
My U.S. Pat. Nos. 3,751,935, 3,893,507 and 3,636,725 also constitute part of the background of this invention. They concern the making of ice rinks by the use of a multiplicity of plastic tubes embedded in a matrix and connected to inlet and outlet headers. A chilled heat-exchange liquid is passed through the tubes to freeze overlaying water to form a rink. In U.S. Pat. No. 3,910,059 also issued to me another array of similar tubes is buried in underlayment beneath the cooling tubes and a lightly heated antifreeze solution is circulated through them to prevent frost buildup and heaving in the ground beneath the rink.
Out of all of this prior art the present invention proposes an inexpensive and efficient coldness storage and utilization system which reduces summer air conditioning costs by using only natural winter cold or at least the coolness of winter air supplemented by low cost mechanical refrigeration. An installation according to the invention is virtually entirely underground and does not preclude other uses of the ground surface above it. Heaving is prevented in spite of the fact that a very large mass of frozen water-soaked soil is employed having a high latent heat of fusion.